Monitoring of an urban lake in the Mediterranean coast after restoration measures

Urban lakes are artificial systems that accomplish many functions, such as storing rainwater, avoiding flooding of adjacent urban areas and supporting recreational activities. However, their intrinsic aesthetic value is usually reduced due to eutrophication problems and anoxia processes. The objective of this study is to present the results of the water quality monitoring of a small urban lake (11264 m² and 1.5 m average depth) in Tavernes de la Valldigna (Valencia, Spain) during summer 2016.  The final aim is to determine the better parameters for monitoring urban lakes having into account budget restrictions. La Goleta lake has suffered repeated events of fish deaths and bad odors that cause the alarm of residents and tourists, especially in summer. Municipal authorities undertook a restoration project which first part was developed during the first semester of 2016. Surveillance monitoring should be financed by the Town Council, so limiting the monitored parameters to the most appropriate ones is key for guarantying long-term surveillance. The results of this study show the importance of macrophyte community in determining water quality and maintaining dissolved oxygen levels. Dissolved oxygen is a key parameter easy to measure and a good indicator of lake water quality evolution. Analytical methodologies must be adapted to the high organic matter content of these systems to avoid interferences.